Focus tube slipping - ground flat tube

[PeterEde]

My tube tension deteriorated to the point where it wouldn't hold jack.
Found a thread describing flattening the supposedly flat area the wheel ran on. Yep certainly was not very flat.
So I flattened it out and not it's nice a tight and stays put until I tell it to move.

Maybe a sticky post for tweaks like this. Nice and simple

[SteveInNZ]

Could you add a link to the thread you found please ?

Steve.

[PeterEde]

http://andysshotglass.com/100EDdrawtube.html

[AG Hybrid]

I did this to my Skywatcher dob focuser draw tube approaching a couple years ago now. Worked with an oil stone gently for an hour or two to flatten it out. The surface area of contact increased by about 5 fold and rendered the need of a focuser upgrade pointless. I hanged 2 kilos worth of equipment of it and it didn't move a millimeter, where before it would slowly slide inwards. Although, I put a Skywatcher electronic focuser on their anyway... because it was cheap.

I've seen the same problem in multiple Skywatcher scopes. Regardless of design. Seems to be one of Skywatcher's/Synta's short comings. People who have done the modification have reported great improvement all the same.

[PeterEde]

Yeah I was thinking crayford but not now. Much tension now. I didn't go completely flat but increased the contacts area by a lot.
Maybe it's one of those things they don't do hoping people will slowly upgrade components?

I honestly can't see how it can be anything buy by design. The flat surface is actually concave like it was made that way

[SteveInNZ]

Thanks for the link Peter.
Like most things that you get a reasonable price, it's probably sufficient for 99% of people who use it visually with equivalently priced, lightweight eyepieces.
You can't fix chromatic aberration with an oilstone so of the two, I'd take the dodgy focuser.

Steve.